CN111433535B

CN111433535B - System and method for controlling purge unit of vapor compression system

Info

Publication number: CN111433535B
Application number: CN201880078321.XA
Authority: CN
Inventors: 大卫·安德鲁·布雷萧; 安德鲁·迈克尔·韦尔奇; 柯蒂斯·C·克莱恩; 凯文·安德鲁·纳尔逊
Original assignee: Johnson Controls Technology Co
Current assignee: Johnson Controls Tyco IP Holdings LLP
Priority date: 2017-10-10
Filing date: 2018-10-04
Publication date: 2021-11-26
Anticipated expiration: 2038-10-04
Also published as: WO2019074764A1; EP3695176B1; US20230228467A1; JP6975325B2; US11635238B2; CN111433535A; KR20200058550A; US20200240685A1; EP3695176A1; JP2020537107A; KR102361926B1

Abstract

A vapor compression system comprising a purge unit fluidly coupled to a condenser of the vapor compression system, wherein the vapor compression system comprises a memory storing instructions and a processor configured to execute the instructions to control operation of the purge unit, wherein the instructions comprise a purge cycle, wherein the instructions of the purge cycle comprise: instructions (286) for enabling the wash unit for a first predetermined period of time; instructions (288) for determining whether one or more evacuations occurred during the first predetermined period of time; instructions (290) for restarting the wash cycle when one or more emptions occurred during the first predetermined period of time; and instructions (292) for deactivating the wash unit for a second predetermined period of time when the processor determines that draining has not occurred during the first predetermined period of time.

Description

System and method for controlling purge unit of vapor compression system

Background

The present application relates generally to vapor compression systems incorporated in air conditioning and refrigeration applications.

Vapor compression systems utilize a working fluid, commonly referred to as a refrigerant, that changes phase between vapor, liquid, and combinations thereof in response to being subjected to different temperatures and pressures associated with operation of the vapor compression system. For example, a heating, ventilation, air conditioning and refrigeration (HVAC & R) system may include a chiller, which is a type of vapor compression system that circulates a refrigerant to remove heat from (e.g., cool) a water stream traversing tubes extending through an evaporator of the chiller. The cooled water flow may be directed to nearby structures to absorb heat (e.g., provide cooling) and then circulated back to the cooler evaporator for re-cooling.

Some coolers utilize low pressure refrigerant and, therefore, a portion of the cooler may be operated at sub-atmospheric pressure. Thus, if there are any defects in this portion of the cooler, non-condensables (e.g., air, atmospheric gases) may enter the cooler and become trapped therein. When present, non-condensables generally reduce the efficiency of the cooler, as the cooler consumes more power in an attempt to maintain cooling capacity.

Some coolers include a purge unit that removes non-condensables from the cooler. For example, the purge unit may include a separate (auxiliary) vapor compression system for cooling and condensing refrigerant from a mixture of refrigerant vapor extracted from the cooler and non-condensables. The purge unit then returns the condensed liquid refrigerant to the chiller and exhausts the non-condensables, while removing these non-condensables returns the chiller efficiency to normal levels. However, the wash unit also consumes power when activated, which may reduce the efficiency of the chiller system.

Drawings

FIG. 1 is a perspective view of a building that may utilize an embodiment of a heating, ventilation, air conditioning and refrigeration (HVAC & R) system in a commercial environment, in accordance with embodiments of the present technique;

FIG. 2 is a perspective view of an embodiment of a vapor compression system in accordance with embodiments of the present technique;

FIG. 3 is a schematic illustration of an embodiment of the vapor compression system of FIG. 2, in accordance with embodiments of the present technique;

FIG. 4 is a schematic illustration of another embodiment of the vapor compression system of FIG. 2, in accordance with embodiments of the present technique;

FIG. 5 is a perspective view of a condenser side of the embodiment of the vapor compression system of FIG. 2, in accordance with embodiments of the present technique;

FIG. 6 is a schematic cross-sectional view of a condenser of the vapor compression system of FIG. 5, in accordance with embodiments of the present technique;

FIG. 7 is a flow chart illustrating an embodiment of a process for activating and deactivating a purge unit of a vapor compression system in response to a particular condition within a condenser, in accordance with embodiments of the present technique;

FIG. 8 is a schematic view of an embodiment of a wash unit in accordance with embodiments of the present technique;

FIG. 9 is a flow chart illustrating an embodiment of a cleaning process of a cleaning unit in accordance with embodiments of the present technique;

FIG. 10 is a flow chart illustrating an embodiment of a standard wash mode of operation of a wash unit in accordance with embodiments of the present technique;

FIG. 11 is a flow chart illustrating an embodiment of an enhanced wash mode of operation of a wash unit in accordance with embodiments of the present technique; and

FIG. 12 is a plot of refrigerant to air ratio in the wash unit versus pump out time in accordance with embodiments of the present technique.

Detailed Description

As set forth above, non-condensables that leak into a vapor compression system (such as a chiller) typically reduce the efficiency of the system. While some vapor compression systems have purge units for removing these non-condensables, purge units typically consume power and, therefore, reduce the efficiency of the system when activated. In view of this, the present embodiments relate to a purge unit of a vapor compression system and a control method thereof, which improve efficiency by: selectively activating and deactivating the wash unit in response to one or more conditions, for example, enables a ratio of refrigerant to air within the wash unit to be within certain industry standards while also minimizing the duration of the wash cycle. As discussed below, these conditions may include conditions within the chiller condenser, the time since the last purge was enabled, the time since the last discharge of non-condensables, and combinations thereof. By reducing the amount of time that the purge unit is activated without removing a significant amount of non-condensables from the vapor compression system, the present embodiments reduce the power consumption of the purge unit, and thus the entire vapor compression system, while also responding to prevent or mitigate efficiency losses due to a significant accumulation of non-condensables in the condenser of the vapor compression system.

Turning now to the drawings, FIG. 1 is a perspective view of an embodiment of an environment for a heating, ventilation, air conditioning and refrigeration (HVAC & R) system 10 in a building 12 for a typical commercial environment. HVAC & R system 10 may include a vapor compression system 14 that supplies a cooling liquid that may be used to cool building 12. The HVAC & R system 10 may also include a boiler 16 to supply warm liquid to heat the building 12 and to circulate air through the air distribution system of the building 12. The air distribution system may also include an air return duct 18, an air supply duct 20, and/or an air handler 22. In some embodiments, the air handler 22 may include a heat exchanger connected to the boiler 16 and the vapor compression system 14 by a conduit 24. The heat exchanger in the air handler 22 may receive heated liquid from the boiler 16 or cooled liquid from the vapor compression system 14, depending on the mode of operation of the HVAC & R system 10. The HVAC & R system 10 is shown with a separate air handler on each floor of the building 12, but in other embodiments the HVAC & R system 10 may include an air handler 22 and/or other components that may be shared between two or more floors.

Fig. 2 and 3 are embodiments of a vapor compression system 14 that may be used in the HVAC & R system 10. The vapor compression system 14 may circulate refrigerant through a circuit beginning with a compressor 32. The circuit may also include a condenser 34, expansion valve(s) or expansion device(s) 36, and a liquid cooler or evaporator 38. Vapor compression system 14 can further include a control panel 40 having an analog-to-digital (a/D) converter 42, a microprocessor 44, a non-volatile memory 46, and/or an interface board 48.

Some examples of fluids that may be used as refrigerants in vapor compression system 14 are Hydrofluorocarbon (HFC) based refrigerants (e.g., R-410A, R-407, R-134a, Hydrofluoroolefins (HFO)), "natural" refrigerants like ammonia (NH3), R-717, carbon dioxide (CO2), R-744, or hydrocarbon based refrigerants, water vapor, or any other suitable refrigerant. In some embodiments, the vapor compression system 14 may be configured to efficiently utilize a refrigerant having a normal boiling point of about 19 degrees celsius (66 degrees fahrenheit) at one atmosphere (relative to an intermediate pressure refrigerant such as R-134a, also referred to as a low pressure refrigerant). As used herein, "normal boiling point" may refer to the boiling point temperature measured at one atmosphere of pressure.

In some embodiments, vapor compression system 14 may use one or more of a Variable Speed Drive (VSD)52, a motor 50, a compressor 32, a condenser 34, an expansion valve or device 36, and/or an evaporator 38. Motor 50 may drive compressor 32 and may be powered by a Variable Speed Drive (VSD) 52. VSD 52 receives Alternating Current (AC) power having a particular fixed line voltage and fixed line frequency from an AC power source and provides power having a variable voltage and frequency to motor 50. In other embodiments, the motor 50 may be powered directly by an AC or Direct Current (DC) power source. The motor 50 may comprise any type of electric motor that may be powered by a VSD or directly from an AC or DC power source, such as a switched reluctance motor, an induction motor, an electronically commutated permanent magnet motor, or another suitable motor.

The compressor 32 compresses a refrigerant vapor and delivers the vapor to the condenser 34 through a discharge passage. In some embodiments, the compressor 32 may be a centrifugal compressor. The refrigerant vapor delivered by the compressor 32 to the condenser 34 may transfer heat to a cooling fluid (e.g., water or air) in the condenser 34. The refrigerant vapor may condense to a refrigerant liquid in the condenser 34 as a result of heat transfer with the cooling fluid. Liquid refrigerant from the condenser 34 may flow through an expansion device 36 to an evaporator 38. In the embodiment illustrated in fig. 3, the condenser 34 is water cooled and includes a tube bundle 54 connected to a cooling tower 56 that supplies a cooling fluid to the condenser.

The liquid refrigerant delivered to the evaporator 38 may absorb heat from another cooling fluid, which may or may not be the same cooling fluid used in the condenser 34. The liquid refrigerant in the evaporator 38 may undergo a phase change from liquid refrigerant to refrigerant vapor. As shown in the illustrated embodiment of fig. 3, the evaporator 38 may include a tube bundle 58 having a supply line 60S and a return line 60R connected to a cooling load 62. A cooling fluid (e.g., water, ethylene glycol, calcium chloride brine, sodium chloride brine, or any other suitable fluid) of the evaporator 38 enters the evaporator 38 via a return line 60R and exits the evaporator 38 via a supply line 60S. Evaporator 38 may reduce the temperature of the cooling fluid in tube bundle 58 via heat transfer with a refrigerant. The tube bundle 58 in the evaporator 38 can include a plurality of tubes and/or a plurality of tube bundles. In any event, vapor refrigerant flows from the evaporator 38 and returns to the compressor 32 through a suction line to complete the cycle.

Fig. 4 is a schematic diagram of the vapor compression system 14 with an intermediate circuit 64 coupled between the condenser 34 and the expansion device 36. The intermediate circuit 64 may have an inlet line 68 fluidly connected directly to the condenser 34. In other embodiments, the inlet line 68 may be indirectly fluidly coupled to the condenser 34. As shown in the illustrated embodiment of fig. 4, inlet line 68 includes a first expansion device 66 positioned upstream of an intermediate vessel 70. In some embodiments, the intermediate vessel 70 may be a flash tank (e.g., a flash intercooler). In other embodiments, the intermediate vessel 70 may be configured as a heat exchanger or "surface economizer" -in the illustrated embodiment of fig. 4, the intermediate vessel 70 functions as a flash tank, and the first expansion device 66 is configured to reduce the pressure (e.g., expand) of the liquid refrigerant received from the condenser 34. During the expansion process, a portion of the liquid may vaporize, and thus the intermediate vessel 70 may be used to separate the vapor from the liquid received from the first expansion device 66. In addition, the intermediate container 70 may further expand the liquid refrigerant as the liquid refrigerant experiences a pressure drop upon entering the intermediate container 70 (e.g., due to a rapid increase in volume upon entering the intermediate container 70). Vapor in the intermediate vessel 70 may be drawn by the compressor 32 through a suction line 74 of the compressor 32. In other embodiments, the vapor in the intermediate vessel may be drawn to an intermediate stage (e.g., not a suction stage) of the compressor 32. Due to the expansion in the expansion device 66 and/or the intermediate container 70, the liquid collected in the intermediate container 70 may be at a lower enthalpy than the liquid refrigerant exiting the condenser 34. Liquid from intermediate vessel 70 can then flow in line 72 through second expansion device 36 to evaporator 38.

It is presently recognized that during operation of the vapor compression system 14, non-condensables (e.g., air, atmospheric gases) that leak into the system tend to accumulate within the condenser 34. Accordingly, as illustrated in fig. 3 and 4, the vapor compression system 14 includes a purge unit 80 fluidly coupled to the condenser 34. As shown, the purge unit 80 receives a purge vapor stream 82 (e.g., a mixture of refrigerant vapor and non-condensables) from the condenser 34. After condensing the refrigerant vapor in the received purge vapor stream 82 to liquid refrigerant and removing non-condensables, the purge unit 80 returns a purge return stream 84 (e.g., condensed liquid refrigerant) to the condenser 34.

In certain embodiments, control panel 40 is communicatively coupled to wash unit 80 such that microprocessor 44 of control panel 40 provides control signals to control the operation of wash unit 80, as discussed in more detail below. For example, in certain embodiments, the control panel 40 may be communicatively coupled to a plurality of sensors of the vapor compression system 14 (e.g., a liquid refrigerant temperature sensor 86, a total pressure sensor 88, other sensors within the purge unit 80). The control panel 40 may provide suitable control signals to activate or deactivate the wash unit 80 in response to data signals received from these sensors, or in response to an amount of time that has elapsed (e.g., the time since the wash unit 80 was last activated, the time since the wash unit 80 last released non-condensables), or a combination thereof.

Fig. 5 is a perspective view of an embodiment of a vapor compression system 14 in accordance with the present technique. More specifically, fig. 5 illustrates a condenser side 90 of the vapor compression system 14. Additionally, fig. 6 is a schematic cross-sectional view of an embodiment of the condenser 34 shown in fig. 5. As illustrated in these figures, the condenser 34 generally includes a discharge baffle 92 and a tube bundle 94 having a plurality of tubes 96 disposed within a shell 98. In addition, the condenser 34 includes a vapor inlet 100 disposed at or near a top 102 of the condenser 34 and a liquid refrigerant outlet 104 disposed at or near a bottom 106 of the condenser. The illustrated condenser 34 also includes a purge effluent outlet 108 and a purge return inlet 110 that extend through the housing 98 and enable gas and liquid flow (e.g., purge vapor flow 82, purge return flow 84) between the interior of the condenser 34 and the purge unit 80.

More specifically, during operation of the vapor compression system 14, the illustrated condenser 34 generally receives a vapor stream 112 (e.g., a refrigerant vapor stream, which may be contaminated with one or more non-condensable gases) through a vapor inlet 100 positioned near a top 102 of the condenser 34. More specifically, as illustrated in fig. 5 and 6, the vapor stream 112 is received from the compressor 32 near a middle 114 or center of a length 116 (e.g., axial length) of the condenser 34. As illustrated, the flow of refrigerant vapor 112 strikes a discharge baffle 92 disposed in an upper portion 118 of the condenser 34 (e.g., above a condenser liquid level 120). The discharge baffle 92 generally directs the flow axially toward the end 126 of the condenser, as indicated by arrow 122. As indicated by arrows 125, vapor stream 112 traverses openings 124 in discharge baffle 92 (e.g., disposed near an end 126 of condenser 34) and then condenses at the surface of condenser tubes 96 of tube bundle 94. The condensed liquid refrigerant accumulates to a particular level (e.g., condenser level 120) before exiting the condenser 34 from a liquid refrigerant outlet 104 positioned near a bottom 106 of the condenser 34 and continuing to circulate through the vapor compression system 14 (e.g., to the expansion device 36 shown in fig. 3).

As illustrated in fig. 6, the tube bundle 94 may define one or more arrangements of layers or rows (such as row 128) of tubes 96. In some embodiments, the tubes 96 of the tube bundle 94 may not include discernible rows (e.g., the tubes 96 of the tube bundle 94 are arranged in a relatively random arrangement). The tubes 96 may be positioned in a fixed spaced arrangement such that each of the tubes 96 are equally spaced from each other. However, in other embodiments, the tubes 96 may be positioned in a variable spacing arrangement such that the distances between the tubes are different from one another. In still other embodiments, the tubes 96 may be positioned at least partially in a fixed spaced arrangement. As such, some of the tubes 96 may be equally spaced from one another, while other tubes 96 are spaced at different distances from one another. It will be appreciated that in other embodiments, any other suitable arrangement of tubes 96 may be used in accordance with the present disclosure.

As mentioned, it is presently recognized that during operation of the vapor compression system 14, non-condensables are generally stagnant anywhere within the upper portion 118 of the condenser 34 (e.g., above the condenser liquid level 120). Accordingly, in certain embodiments, the purge vapor stream 82 is extracted from a purge extraction outlet 108 of the condenser 34 disposed at any suitable location within the upper portion 118 of the condenser 34, which is directed to a purge vapor inlet 130 of the purge unit 80 to remove these non-condensables. Additionally, for the illustrated embodiment, the purge unit 80 includes a gravity-fed drain (e.g., purge return outlet 132) to return the flow of condensed liquid refrigerant 84 to the condenser 34 via a drain line 133. Thus, the illustrated condenser 34 includes a purge return inlet 110 positioned a vertical distance 134 below a purge return outlet 132 of the purge unit 80 and above the condenser liquid level 120.

Further, in certain embodiments, the purge return outlet 132, the purge return inlet 110, and/or the drain line 133 may include at least one isolation feature 135. For example, in certain embodiments, the isolation feature 135 may be a solenoid valve, a check valve, a p-well, or a combination thereof. For the embodiment shown, the isolation feature 135 operates by selectively isolating the wash unit 80 from the cooler (e.g., from the condenser 34), particularly when the wash unit 80 is removing non-condensables that have been separated from the refrigerant (e.g., when the vacuum pump 190 is activated, as discussed below with respect to fig. 8). For embodiments in which the isolation feature 135 is an actively controlled solenoid valve or other actively controlled feature, the isolation feature 135 is communicatively coupled to suitable control circuitry (e.g., control panel 40) that provides signals to control the operation (e.g., opening and closing) of the isolation feature 135 to selectively allow or prevent fluid flow between the purge return outlet 132 and the purge return inlet 110.

It will be appreciated that in other embodiments, the purge return outlet 132 may instead be fluidly coupled to the evaporator 36, and may instead return a flow of condensed liquid refrigerant 84 to the evaporator without substantially affecting the performance of the vapor compression system 14. It will also be appreciated in light of this disclosure that in various embodiments, the wash unit 80 may be disposed on the same side of the condenser 34 as the evaporator 38 (e.g., positioned between the condenser 34 and the evaporator 38), or disposed inside the condenser 34 (e.g., opposite the evaporator 38), or in any other suitable location. Thus, for such embodiments, the purge extraction outlet 108 and/or the purge reflux inlet 110 may similarly be disposed on the same side of the condenser 34 as the evaporator 38 (e.g., between the condenser 34 and the evaporator 38).

The exemplary embodiment of condenser 34 illustrated in fig. 6 also includes a liquid refrigerant temperature sensor 136 and a total pressure sensor 138 (e.g., a pressure transducer 138). As illustrated, the liquid refrigerant temperature sensor 136 is disposed below the condenser liquid level 120 to ensure that the temperature of the liquid refrigerant in the condenser 34 can be properly measured. As shown, a total pressure sensor 138 is disposed above the condenser liquid level 120 (e.g., in the upper portion 118 of the condenser 34) to ensure that the total pressure of refrigerant and non-condensables in the upper portion 118 of the condenser 34 can be properly measured. In certain embodiments, the liquid refrigerant temperature sensor 136 and the total pressure sensor 138 provide data signals to the microprocessor 44 or other suitable processing circuitry of the control panel 40 such that the microprocessor 44 of the control panel 40 can activate and deactivate the wash unit 80 based at least in part on the measurements of the

sensors

136 and 138.

By way of specific example, fig. 7 illustrates an example embodiment of a process 150 that may be performed by microprocessor 44 of control panel 40 or other suitable processing circuitry of vapor compression system 14 (e.g., via executable instructions stored in a memory) to determine when to selectively activate and deactivate wash unit 80 in response to particular conditions within condenser 34. It will be appreciated in light of this disclosure that other control strategies may additionally or alternatively be used. The process 150 shown in fig. 7 begins with the microprocessor 44 receiving (block 152) a data signal from the liquid refrigerant temperature sensor 136 indicative of the temperature of the liquid refrigerant in the condenser 34. In certain embodiments, the microprocessor 44 uses the temperature indicated by the liquid refrigerant temperature sensor 136 as a direct indication or representation of the Observed Condenser Saturation Temperature (OCST). The microprocessor 44 also receives (block 154) a data signal from the total pressure sensor 138 of the condenser 34. The microprocessor 44 then determines (block 158) a Predicted Condenser Saturation Temperature (PCST) of the condenser 34. For example, the microprocessor 44 may access a look-up table or use a mathematical formula stored in the non-volatile memory 46 of the control panel 40 that relates the measured total pressure to the PCST to determine or calculate the PCST for a particular refrigerant of the vapor compression system 14.

Continuing with the process 150 illustrated in fig. 7, the microprocessor 44 then compares (block 158) the OCST and PCST determined in the above block. In the event that microprocessor 44 determines that the OCST (from box 152) is greater than the PCST (from box 156) by more than a certain threshold amount or deviation (e.g., 0.5 ° F, 0.75 ° F, 1 ° F), microprocessor 44 enables (box 160) purge unit 80 if or when purge unit 80 has not been enabled. In certain embodiments, microprocessor 44 or other suitable processing circuitry may enable purge unit 80 for a specified length of time or purge duration (e.g., 1 hour, 2 hours, 6 hours, 12 hours), until certain condenser conditions are met (e.g., until PCST is again within the threshold of OCST), until purge unit 80 has stopped releasing non-condensables for a predetermined amount of time, or some combination thereof. For the embodiment illustrated in fig. 7, in the event that microprocessor 44 determines (block 158) that OCST is not greater than PCST by more than a certain amount threshold or deviation, microprocessor 44 interrupts (e.g., deactivates, stops) (block 162) purge unit 80 if or when purge unit 80 is enabled. In other embodiments, microprocessor 44 or other suitable processing circuitry may provide suitable control signals to activate and deactivate purge unit 80 based on a comparison of OCST and PCST as described, as well as another factor (e.g., the amount of time since purge unit 80 was activated, the amount of time since purge unit 80 released non-condensables, etc.).

FIG. 8 is a schematic diagram illustrating an embodiment of a wash unit 80 in accordance with the present techniques. The illustrated purge unit 80 includes a separate (e.g., auxiliary) vapor compression system 170 relative to the main vapor compression system 14 (e.g., chiller 14) being purged. As such, the illustrated embodiment of the purge unit 80 includes a compressor 172, a condenser 174 with a fan 176, a filter dryer 178, an expansion valve 180, and an evaporator coil 182 that are fluidly coupled together to form a refrigeration loop or circuit 184 of the illustrated embodiment of the vapor compression system 170.

When the wash unit 80 illustrated in fig. 8 is activated, after a refrigerant (e.g., R404a or another suitable refrigerant) is liquefied by the combined action of the compressor 172 and the condenser 174, the refrigerant is introduced into the evaporator coil 182 disposed within the wash tank 186 to condense the wash vapor stream 82 entering the wash tank 186. More specifically, for the illustrated embodiment, the purge tank 186 receives a purge vapor stream 82 (e.g., a supply of refrigerant vapor and non-condensables) from a purge extraction outlet 108 of the condenser 34 of the main vapor compression system 14 (e.g., the cooler 14). The refrigerant vapor in the purge vapor stream 82 that condenses within the purge tank 186 is returned to the purge return inlet 110 of the condenser 34 as a purge return stream 84 (e.g., a stream of liquid refrigerant). Subsequently, the non-condensable gases 188 in the purge vapor stream 82 received from the main vapor compression system 14 that are not condensed within the purge tank 186 are removed by a vacuum pump 190, as discussed in more detail below.

The wash unit 80 shown in fig. 8 includes a controller 192 communicatively coupled to the various components of the wash unit 80 to control the operation (e.g., enable, disable, purge) of the wash unit 80. For the illustrated embodiment, the controller 192 includes a memory 194 that stores instructions and a processor 196 that executes the instructions to control the operation of the wash unit 80. In other embodiments, the controller 192 may be the control panel 40 and the microprocessor 44 may execute instructions stored in the non-volatile memory 46 to control the operation of the purge unit 80 in addition to the main vapor compression system 14 and/or the HVAC & R system 10 as discussed above. In certain embodiments, controller 92 may be distinct from control panel 40 and communicatively coupled thereto to exchange data and/or control signals. For example, in such embodiments, processor 196 of controller 192 may send data signals to microprocessor 44 of control panel 40 to indicate whether wash unit 80 is enabled and to indicate any error messages or notifications generated by wash unit 80 during operation, as discussed in more detail below. Similarly, in such embodiments, the microprocessor 44 of the control panel 40 may send data signals to the processor 196 of the controller 192 to indicate measured or calculated parameters of the main vapor compression system 14 (e.g., measured condenser liquid temperature, measured condenser pressure, calculated condenser saturation temperature) so that the controller 192 may determine when to selectively activate and deactivate the purge unit 80, as discussed in detail below.

For the embodiment illustrated in FIG. 8, the controller 192 is communicatively coupled to receive data signals from and/or provide control signals to the various components of the wash unit 80. For example, the processor 196 of the controller 192 may activate the wash unit 80 by providing appropriate control signals to activate the fan 176 and compressor 172 of the condenser 174. The processor 196 of the controller 192 may provide suitable control signals to actuate the first solenoid valve 198, which remains in the open position except during evacuation of the non-condensables by the vacuum pump 190, as discussed below. Similarly, the processor 196 of the controller 192 may provide suitable control signals to actuate the second solenoid valve 200, which remains in a closed position except during evacuation of non-condensables by the vacuum pump 190, as discussed below. The controller 192 may also provide suitable control signals to enable and disable the vacuum pump 190 (e.g., operate the vacuum pump 190 for a predetermined amount of evacuation time before disabling the pump). Further, the illustrated controller 192 may receive data signals from a level sensor 199 indicative of the level of condensed liquid refrigerant in the wash tank 186.

Additionally, for the embodiment of the wash unit 80 shown in fig. 8, the processor 196 of the controller 192 is communicatively coupled to at least two temperature sensors. The first temperature sensor 202 measures the temperature of the wash unit refrigerant exiting the evaporator coil 182 (T1) and the second temperature sensor 204 measures the temperature of the wash unit refrigerant entering the evaporator coil 182 of the wash unit 80 (T2). It is presently recognized that when the evaporator coil 182 is condensing refrigerant vapor from the main vapor compression system 14, generally the T1 increases (e.g., increases absolutely or relative to the T2). However, when the purge tank 186 includes a large amount of non-condensable gases, T1 may decrease (e.g., approaching T2). Thus, as set forth below, the processor 196 or other suitable processing circuitry of the controller 192 determines when to empty the wash tank 186 based at least on T1. For example, in certain embodiments, the processor 196 of the controller 192 may compare T1 to a predetermined threshold (e.g., 15 degrees fahrenheit (° F)) and initiate draining of the wash tank 186 when T1 is below (e.g., less than) the predetermined threshold. In other embodiments, the processor 196 of the controller 192 may compare the difference between T1 and T2 to a predetermined threshold (e.g., 0.5 ° F, 1 ° F, 5 ° F) and initiate draining of the wash tank 186 when the difference between T1 and T2 is below (e.g., less than) the predetermined threshold.

For example, fig. 9 is a flow chart illustrating an example embodiment of a purge process 220 by which the processor 196 of the controller 192 of the purge unit 80 or other suitable processing circuitry of the vapor compression system 14 operates the purge unit 80. It is understood that in other embodiments, process 220 may include additional steps, omit illustrated steps, involve performing multiple steps simultaneously, and/or involve performing steps in a different order than illustrated in fig. 9. For the illustrated example, the process 220 is performed when the microprocessor 44 of the control panel 40 or the processor 196 of the controller 192 requests or triggers the activation of the wash unit 80 for a specified amount of time (referred to herein as a wash duration) or an unlimited amount of time (e.g., until interrupted).

The illustrated cleaning process 220 begins with the processor 196 resetting (block 222) a counter that tracks the number of emptions of the cleaning tank 186 during the current cleaning process and recording the start time of the cleaning process. The processor 196 provides (block 224) appropriate control signals to the compressor 172 and condenser fan 176 of the wash unit 80 to enable both devices, thereby enabling the wash unit 80. The processor 196 further provides (block 226) appropriate control signals to open the first solenoid valve 198 (e.g., if it is determined that the first solenoid valve is closed) and close the second solenoid valve 200 (e.g., if it is determined that the second solenoid valve is open).

The embodiment of the process 220 shown in fig. 9 continues with the processor 196 receiving (block 228) a signal from the first temperature sensor 202 indicative of the temperature of the wash unit refrigerant leaving the evaporator coil 182 of the wash unit 80 (T1). The processor 196 analyzes T1 to determine if an evacuation of the wash tank 186 should occur. For the exemplary embodiment, processor 196 determines (block 230) whether T1 is less than a predetermined temperature threshold (e.g., 15 ° F). In other embodiments, the processor 196 may compare the difference between T1 and T2 to different predetermined thresholds (e.g., 5 ° F, 10 ° F, 15 ° F).

When the processor 196 determines that T1 has fallen below the predetermined temperature threshold, the processor 196 provides an appropriate control signal to initiate or initiate draining of the wash tank 186 (as indicated by the step in bracket 232). For example, as illustrated, the processor 196 provides (block 234) a control signal to activate the vacuum pump 190 for a predetermined amount of evacuation time (e.g., 30 seconds, 45 seconds, 1 minute) and provides (block 236) a control signal to close the first solenoid valve 198 and open the second solenoid valve 200. The processor 196 further increments the purge count (block 238) and restarts the process 220 at block 222.

For the illustrated example, when T1 is above the predetermined temperature threshold in block 230, then processor 196 determines (block 240) whether the purge duration has expired or a purge interrupt has been requested. For example, as illustrated, the processor 196 may compare the current time to the wash start time recorded in block 222 to determine whether the wash duration has expired. The processor 196 may further check to see if it has determined that the wash unit should be interrupted due to a change in conditions within the condenser (e.g., according to

blocks

158 and 160 of fig. 7). If the purge duration has not expired and the purge process has not been interrupted, processor 196 continues to receive (block 228) a signal indicative of T1 and continues to determine (block 230) whether T1 has risen above the predetermined temperature threshold until the purge duration expires or the purge process is interrupted (block 240). The processor 196 then provides (block 242) appropriate control signals to deactivate the compressor 172 and condenser fan 176 of the wash unit 80, thereby deactivating the wash unit 80. Additionally, as illustrated, the processor 196 may record in the memory 194 the end time of the purge and the purge count of the time the purge process 220 is performed.

In certain embodiments, the processor 196 or other suitable processing circuitry of the controller 192 of the wash unit 80 may enable the wash unit 80 in a standard wash mode of operation. An exemplary embodiment of a standard purge mode process 260 is shown in FIG. 10. In other embodiments, the indicated purge duration and wait duration may be longer or shorter depending on the nature of the main vapor compression system 14. It is understood that in other embodiments, process 260 may include additional steps, omit illustrated steps, involve performing multiple steps simultaneously, and/or involve performing steps in a different order than illustrated in fig. 10.

As shown, the process 260 begins by enabling (block 262) a cleaning process (e.g., the cleaning process 220 shown in fig. 9) for a predetermined cleaning duration (e.g., 2 hours). As set forth above, after the washing process 220 is completed, the memory 194 of the controller 192 may store the washing count and the washing end time. Thus, continuing with the process 260 illustrated in FIG. 10, the processor 196 then considers the wash count value to determine (block 264) whether any draining of the wash tank 186 occurred during the enabling of the wash process of block 262. If the purge count indicates that one or more purges did occur, the processor 196 re-enables the purge process 220 for the purge duration (e.g., 2 hours) (block 262). If the wash count indicates that no draining has occurred (e.g., the step in bracket 232 of the wash process 220 has not been performed), the processor 196 may proceed to the next step in the process 260.

For the illustrated embodiment, once the wash unit 80 has been enabled for the wash duration (e.g., 2 hours) (block 262) without any draining (block 264), the processor 196 may wait at block 266 until a particular set of conditions is met. For the illustrated example embodiment, the processor 196 receives data from a communicatively coupled sensor (e.g., liquid refrigerant temperature sensor 136, total pressure sensor 138 illustrated in fig. 6) disposed inside the condenser 34 of the main vapor compression system 14, or from another communicatively coupled processor that has access to this data, to determine the OCST and PCST of the condenser 34, as discussed above. Using these values, processor 196 determines (block 266) whether OCST is greater than PCST by more than a threshold or deviation value (DEV) (e.g., greater than 0.5 ° F). When this condition is met, or when the wash unit 80 is deactivated for at least a predetermined wait duration (e.g., 6 hours based on the wash stop time) (block 266), the processor 196 proceeds to the next step of the process 260.

For the embodiment shown, the process 260 continues with re-enabling (block 268) the cleaning process for a cleaning duration (e.g., 2 hours). The processor 196 then considers the purge count to determine (block 270) whether any purging occurred during the purge process initiated at block 268. As illustrated, if the processor 196 determines that any draining of the wash tank 186 has occurred, the processor 196 proceeds back to block 262 of the process 260. When the processor 196 determines that no draining has occurred (e.g., the step in bracket 232 of the cleaning process 220 has not been performed), then the processor 196 may wait for a wait duration (e.g., 6 hours) with the cleaning unit 80 deactivated (block 272) before proceeding back to block 262 of the process 260. Thus, the embodiment of the standard purge mode process 260 illustrated in FIG. 10 limits the amount of time the purge unit 80 is enabled, thereby reducing power consumption and increasing the efficiency of the main vapor compression system 14 and the HVAC & R system 10.

In certain embodiments, the processor 196 or other suitable processing circuitry of the controller 192 of the wash unit 80 may enable the wash unit 80 in an enhanced wash mode of operation. An exemplary embodiment of an enhanced cleaning mode process 280 is illustrated in fig. 11. In other embodiments, the indicated purge duration and wait duration may be longer or shorter depending on the nature of the main vapor compression system 14 (e.g., the chiller 14). It is understood that in other embodiments, process 280 may include additional steps, omit illustrated steps, involve performing multiple steps concurrently, and/or involve performing steps in a different order than illustrated in fig. 11.

As illustrated, the process 280 begins by resetting (block 282) a counter for the number of days since the last emptying of the wash tank 186, and resetting (block 284) the counter for the number of wash cycles (of the day). Subsequently, the processor 196 enables (block 286) a cleaning process (e.g., the cleaning process 220 shown in fig. 9) for a predetermined cleaning duration (e.g., 1 hour). As indicated by block 288, if the wash count indicates that at least one drain occurred during the wash process of block 286, the processor 196 again resets (block 290) the counter for the number of days since the last drain and proceeds back to block 284.

Continuing with the illustrated embodiment, when the processor 196 determines (block 288) that no draining occurred during the wash process of block 286 (e.g., the step in bracket 232 of the wash process 220 was not performed), then the processor 196 increments the wash unit cycle count and waits for a first predetermined wait duration (e.g., 4 hours) if the wash unit 80 is deactivated (block 292). After waiting, the processor 196 determines (block 293) whether the wash unit cycle is greater than or equal to a predetermined value (e.g., 3), and if not, the processor 196 returns to block 286 to perform the wash process again for the wash duration (e.g., 1 hour). When the processor 196 determines (block 293) that draining of the wash tank 186 has not occurred, then the processor 196 increments (block 294) the number of days since the last drain and waits for a second wait time (e.g., 24 hours) with the wash unit 80 deactivated, wherein the second wait time duration is significantly longer than the first wait time duration. For example, in one embodiment, when the processor 196 determines that a drain has not occurred during three or more one-hour activations of the washing process (with four hours of washing unit deactivation between each activation), then the processor 196 increments the number of days since the last drain and waits 24 hours with the washing unit 80 deactivated.

Continuing with the illustrated embodiment, once the second wait duration expires, the processor 196 may determine (block 296) whether the number of days since last emptying is greater than or equal to a predetermined number of days (e.g., 1 week). If not, the processor 196 proceeds back to block 284. When the processor 196 again determines (block 293) that draining of the wash tank 186 has not occurred during repeated activations of the wash process, then the processor 196 again increments (block 294) the number of days since the last drain and waits for a second wait duration (e.g., 24 hours) with the wash unit deactivated. For example, in one embodiment, when the processor 196 determines that draining has not occurred during three or more one-hour wash activations (with four hours of wash unit deactivation between each activation), then the processor 196 increments the number of days since the last drain and waits 24 hours with the wash unit deactivated.

Thus, for the illustrated embodiment, when the processor 196 determines (block 296) that draining of the wash tank 186 has not occurred during a predetermined amount of time (e.g., 1 week) of a daily wash program (e.g., at least three times an hour on a wash process with four hours on interval), then the processor 196 waits (block 298) for a third wait duration (e.g., 7 days) with the wash unit 80 deactivated before proceeding back to block 284 of the process 280, wherein the third wait duration is significantly longer than the first wait duration and the second wait duration. As shown, the processor 196 then executes a single-day washing procedure as discussed above (e.g., at least three times an hour on a washing process, four hours apart). If no draining of the wash tank 186 has occurred, since the number of days since the last drain remained greater than the predetermined number of days (e.g., 7 days), the processor 196 again waits (block 298) for a third duration (e.g., 1 week) with the wash unit 80 deactivated before proceeding back to process 280, block 284. Thus, the embodiment of the enhanced wash mode process 280 shown in FIG. 11 greatly limits the amount of time the wash unit 80 is enabled (e.g., as compared to the standard wash mode process 260 shown in FIG. 10). More specifically, the enhanced purge mode process 280 achieves a substantial increase in the efficiency of the vapor compression system 14 by selectively disabling the purge unit 80 when non-condensable is not actively removed from the main vapor compression system 14 (e.g., when no purging of the purge tank 186 occurs). In this way, the process 280 illustrated in fig. 11 can further reduce the power consumption and increase the efficiency of the main vapor compression system 14 and the HVAC & R system 10.

It will be appreciated that various error or problem conditions may be encountered during operation of the wash unit 80, and in response, the processor 196 of the controller 192 of the wash unit 80 may provide control signals to generate a warning message to be provided to an occupant or technician. For example, during execution of the cleaning process 220 of fig. 9, if the processor 196 determines that T2 has increased above a first threshold temperature (e.g., 5 ° F), the processor 196 of the cleaning unit 80 may send an appropriate signal to provide a warning that the expansion valve 180 (as illustrated in fig. 8) of the cleaning unit 80 may need to be adjusted. If processor 196 determines that T2 has increased above a second threshold temperature (e.g., 10F.), processor 196 of cleaning unit 80 may send an appropriate signal to again provide a warning that the expansion valve of cleaning unit 80 may need to be adjusted or that second temperature sensor 204 may be defective, and may send a control signal to deactivate cleaning unit 80. If the processor 196 determines that the level sensor 199 indicates that the level of condensed liquid refrigerant in the wash tank 186 is above a certain threshold, the processor 196 may provide an appropriate signal to deactivate the wash unit for 1 minute when refrigerant drains back into the condenser 34 of the main vapor compression system 14 and provide a warning that the wash unit 80 is temporarily deactivated. In certain embodiments, if the processor 196 determines that the number of purges (e.g., purge counts) over a 24 hour period is greater than a threshold (e.g., 10, 20, 30, 40), the processor 196 provides a warning indicating that the daily purge count limit has been exceeded and that a leak may be present in the main vapor compression system 14. Additionally, in certain embodiments, if processor 196 determines that the OCST remains greater than PCST for at least the DEV value for 24 consecutive hours, processor 196 may provide a warning indicating that air may be present in main vapor compression system 14 and that maintenance should be performed on purge unit 80.

It will also be appreciated that in some embodiments, the processor 196 of the controller 192 may be programmed to switch between different modes of operation. For example, in certain embodiments, the processor 196 is capable of switching between the standard purge mode process 260 and the enhanced purge mode process 280 as discussed above (e.g., in response to input from a user or technician, in response to conditions within the vapor compression system 14). Additionally, in certain embodiments, the processor 196 may support the use of other wash unit operating modes during installation, maintenance, and/or repair of the main vapor compression system 14 or the HVAC & R system 10. For example, in certain embodiments, in the service mode, the processor 196 may accept input from a communicatively coupled user input device to enable the washing process 220 (e.g., as shown in fig. 9) for an indicated washing duration (e.g., 12 hours, 24 hours, 72 hours, etc.). In some embodiments, in the manual mode, the processor 196 may accept an input from a communicatively coupled user input device to enable the washing process without a explicit duration until another input (e.g., an interrupt signal) is received to disable the washing process. It will be appreciated that one or more error or problem conditions (e.g., daily wash count limits) may be suppressed when operating in the service mode or the manual mode.

The purge unit 80 is discussed above with respect to fig. 3 and 4 as being fluidly coupled to the condenser 34 to receive a purge vapor stream 82 (e.g., a mixture of refrigerant vapor and non-condensables) from the condenser 34 and return condensed liquid refrigerant to the condenser 34 in a purge return stream 84 (without non-condensables). It is presently recognized that certain locations within the interior volume of condenser 34 are significantly better at extracting (e.g., picking up, removing) purge vapor stream 82 in terms of the efficiency of the purge unit and purge process 220, in addition to where condenser 34 is a location where non-condensables accumulate in main vapor compression system 14.

For example, returning to fig. 5 and 6, it is presently recognized that certain locations within the upper portion 118 of the condenser 34 are particularly turbulent, resulting in a higher content of refrigerant relative to non-condensables. As such, it is presently recognized that locating the clean effluent extraction port 108 at a particular location within the upper portion 118 of the condenser 34 enables improved cleaning efficiency as compared to other locations. For example, prior to the present disclosure, the purge extraction outlet 108 was located near the top 102 of the condenser 34 (e.g., near the end 126 of the condenser 34), such as at the location indicated by arrow 300 in fig. 5. Other purge extraction outlet locations include near the end of the condenser 34, directly above the condenser liquid level 120, as indicated by arrow 302. However, it is presently recognized that these locations are also particularly turbulent regions inside the condenser 34, although these locations may include non-condensables and may be used to extract the purge vapor stream 82 from the condenser 34. As such, positioning the purge effluent extraction port 108 near these locations relative to other locations involves the purge unit 80 operating for a longer period of time to substantially purge the vapor compression system 14 of non-condensable.

In contrast, as illustrated in fig. 5 and 6, the presently disclosed purge extraction outlet 108 is generally disposed below the discharge baffle 92 and above the condenser liquid level 120. More specifically, in certain embodiments, the purge extraction outlet 108 is located below the discharge baffle 92 and near the middle or center 114 of the length 116 of the condenser 34. As best shown in fig. 6, in certain embodiments, this corresponds to positioning the clear eluate extraction port 108 away from the top 102 of the condenser 34 and above the condenser liquid level 120. More specifically, the illustrated clear eluate extraction outlet 108 may be described as being in the middle or near the center 304 of the height 306 (e.g., vertical height) of the condenser 34 (e.g., near the condenser tubes 96 of the tube bundle 94). It is presently recognized that positioning the purge effluent extraction port 108 as currently taught greatly improves the efficiency of the purge unit 80, as well as the efficiency of the vapor compression system 14 and the HVAC & R system 10. For example, positioning the clean eluate extraction outlet 108 as currently disclosed enables a wash activation of about one hour to the same effect as a wash activation of about 12 hours at a different wash extraction location (such as the top 102 of the condenser 34).

In certain embodiments, during operation of the purge unit 80, the temperature and pressure in the purge tank 186 may be used to describe the ratio of refrigerant to air in the vapor portion of the purge tank 186. For example, as illustrated in fig. 8, in certain embodiments, at least one temperature sensor 308 and at least one pressure sensor 310 may be disposed within the vapor portion 312 of the purge tank 186 (e.g., above the liquid level 314 in the purge tank 186), and the controller 192 may use measurements from the temperature sensor 308 and the pressure sensor 310 to determine a ratio of the mass of refrigerant in the vapor portion 312 of the purge tank 186 to the mass of air in the vapor portion 312 of the purge tank 186.

During pumping of the gas from the wash tank 186, the pumping flow may be combined with continued condensation on the evaporator coil 182 in the wash tank 186. In the case where the purge tank 186 includes a liquid seal in the drain, the liquid is boiled to replace the condensed volume and pump it out of the cooler 14. Conversely, where a liquid seal is not included in the drain of the purge tank 186, a flow is generated from the condenser through the drain line to replace the volume. In both cases, the ratio of refrigerant in the pumped gas will increase throughout the purge cycle.

In certain embodiments, the duration of the purge cycle may be shortened to a period of time where modeling and testing shows that the average pumped refrigerant to air ratio meets certain requirements of existing industry standards (such as ASHRAE147/AHRI 580). For example, the controller 192 may receive temperature and pressure measurements from the temperature sensor 308 and the pressure sensor 310, and may use these temperature and pressure measurements in conjunction with a dynamic model of the wash operation in the wash unit 80 (e.g., in some embodiments the wash tank 186) to determine when the refrigerant to air ratio in the wash unit 80 (e.g., in some embodiments the wash tank 186) meets certain requirements of existing industry standards, such as ASHRAE147/AHRI 580. For example, in certain embodiments, the controller 192 may determine a minimum duration of the wash cycle of the wash unit 80 (including a minimum duration of the pump-out time) that enables a ratio of refrigerant to air in the wash unit 80 (e.g., in the wash tank 186, in certain embodiments) to meet at least one industry standard.

In such embodiments, for example, the pump-out time of the vacuum pump 190 may be reduced from about 30 seconds to between about 5 seconds and about 10 seconds, between about 4 seconds and about 15 seconds, or between about 3 seconds and about 20 seconds. Additionally, the temperature within the purge tank 186 can be reduced by varying the suction temperature at pump start up and the coil saturation temperature. In doing so, as illustrated in fig. 12, the refrigerant to air ratio in the purge tank 186 may be significantly reduced, for example, to less than about 2.5, less than about 2.0, less than about 1.5, or even lower (e.g., about 1.0). As will be understood by those skilled in the art, the term "about" as used herein is intended to refer to a characteristic that is very close to the stated value. For example, some characteristics that "about" equal some of the stated values may be within an acceptable tolerance of +/-5% of the stated value, +/-4% of the stated value, +/-3% of the stated value, +/-2% of the stated value, +/-1% of the stated value, or even less. As one non-limiting example, the embodiments described herein may enable the ratio of refrigerant to air in the purge tank 186 to be significantly reduced to about 1.0 (e.g., between 0.95 and 1.05, assuming a tolerance of +/-5%).

In certain embodiments, the suction pressure of the compressor 172 of the auxiliary vapor compression system 170 may be controlled by the constant pressure expansion valve 316 to a very low saturated refrigerant pressure for the auxiliary refrigerant. In certain embodiments, the purging refrigerant may be a cryogenic refrigerant (such as R404a or R134a), or other refrigerant capable of being used at cryogenic temperatures (such as propane, R1270, R1234yf, R1234ze, R407A, R452A, or the like).

Again, in such embodiments, the compressor 172 may be designed for relatively low temperatures, which allows for a lower partial pressure of the refrigerant in the purge tank 186, resulting in a lower ratio of refrigerant to air in the purge tank 186. In addition, the shorter duration of the pump-out cycle minimizes the effect of the flow of replacement refrigerant into the purge tank 186 on the overall refrigerant to air ratio in the purge tank 186. The embodiments described herein enable existing industry standards related to refrigerant to air ratios to be met without the additional cost of certain equipment, such as a discharge tank or the like.

Although only certain features and embodiments have been shown and described, many modifications and changes may occur to those skilled in the art (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters (e.g., temperatures, pressures, etc.), mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the claims. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the disclosure. Furthermore, in an effort to provide a concise description of the exemplary embodiments, all features of an actual implementation may not have been described (i.e., those unrelated to the presently contemplated best mode of carrying out the disclosure, or those unrelated to enabling the claimed disclosure). It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure, without undue experimentation.

Claims

1. A vapor compression system comprising a purge unit fluidly coupled to a condenser of the vapor compression system, wherein the vapor compression system comprises a memory storing instructions and a processor configured to execute the instructions to control operation of the purge unit, wherein the instructions comprise a purge cycle, wherein the instructions of the purge cycle comprise:

instructions for enabling the wash unit for a first predetermined period of time;

instructions for determining whether one or more evacuations occurred during the first predetermined period of time;

instructions for restarting the wash cycle when one or more emptions occurred during the first predetermined period of time;

instructions for deactivating the wash unit for a second predetermined period of time when the processor determines that draining has not occurred during the first predetermined period of time; and

instructions for repeatedly performing the wash cycle a predetermined number of times, and then deactivating the wash unit for a third predetermined period of time when no draining has occurred during the performance of the wash cycle.

2. The vapor compression system of claim 1, wherein the first predetermined period of time is one hour.

3. The vapor compression system of claim 1, wherein the second predetermined period of time is four hours.

4. The vapor compression system of claim 1, wherein the predetermined number of times is at least three times.

5. The vapor compression system of claim 1, wherein the third predetermined period of time is 24 hours.

6. The vapor compression system of claim 1, wherein the instructions include instructions to perform the purge cycle at least once a day for a week, and then deactivate the purge unit for a week when no purging has occurred during performance of the purge cycle.

7. The vapor compression system of claim 6, wherein the instructions include instructions to re-execute the purge cycle at least once and then deactivate the purge unit for another week when no purging has occurred during execution of the purge cycle.

8. The vapor compression system of claim 1, wherein the instructions to activate the purge unit comprise instructions to provide control signals to activate a compressor and a condenser fan of the purge unit, and wherein the instructions to deactivate the purge unit comprise instructions to provide control signals to deactivate the compressor and the condenser fan of the purge unit.

9. The vapor compression system of claim 8, wherein the instructions for enabling the purge unit comprise:

instructions for receiving a temperature of a wash unit refrigerant exiting an evaporator coil of the wash unit; and

instructions for evacuating a wash tank of the wash unit based on a change in the temperature of the wash unit refrigerant exiting the evaporator coil.

10. The vapor compression system of claim 9, wherein the instructions for evacuating the purge tank based on the change in the temperature of the purge unit refrigerant exiting the evaporator coil comprise: instructions for draining the wash tank when the temperature of the wash unit refrigerant exiting the evaporator coil is less than a minimum temperature threshold.

11. The vapor compression system of claim 9, wherein the instructions for evacuating the purge tank based on the change in the temperature of the purge unit refrigerant exiting the evaporator coil comprise:

instructions for receiving a temperature of the wash unit refrigerant entering the evaporator coil of the wash unit;

instructions for determining a difference between the temperature of the wash unit refrigerant exiting the evaporator coil and the temperature of the wash unit refrigerant entering the evaporator coil; and

instructions for draining the purge tank when the difference is less than a threshold amount.

12. The vapor compression system of claim 9, wherein the instructions for evacuating the purge tank comprise:

a command for closing a first solenoid valve of the purge unit disposed between the condenser and the purge unit;

instructions for disconnecting a second solenoid valve of the cleaning unit disposed between a cleaning tank of the cleaning unit and a vacuum pump of the cleaning unit;

instructions for enabling the vacuum pump for a predetermined evacuation time.

13. A vapor compression system comprising a purge unit fluidly coupled to a condenser of the vapor compression system, wherein the vapor compression system comprises a processor configured to:

(A) activating the cleaning unit for a predetermined cleaning duration; then the

(B) Continuing to return to step (a) in response to determining that at least one wash unit drain occurred during step (a), or deactivating the wash unit for a first predetermined wait time in response to determining that no wash unit drain occurred during step (a); then the

(C) Continuing to return to step (a) a first predetermined number of times and then deactivating the wash unit for a second predetermined wait time in response to determining that no draining has occurred; and then

(D) Continuing to return to step (a) a second predetermined number of times and then deactivating the wash unit for a third predetermined wait time in response to determining that no draining has occurred.

14. The vapor compression system of claim 13, wherein the predetermined purge duration is at least one hour.

15. The vapor compression system of claim 13, wherein the first predetermined wait time is four hours.

16. The vapor compression system of claim 13, wherein the first predetermined number of times is three, the second predetermined wait time is 24 hours, and wherein the third predetermined wait time is one week.

17. The vapor compression system of claim 13, wherein the processor is further configured to:

(E) starting the cleaning unit, wherein the cleaning duration of the cleaning unit is the preset cleaning duration; and then

(F) Continuing to return to step (a) in response to determining that at least one wash unit drain occurred during step (E), or deactivating the wash unit for a fourth predetermined wait time in response to determining that no wash unit drain occurred during step (E).

18. The vapor compression system of claim 17, wherein the fourth predetermined wait time is one week.

19. The vapor compression system of claim 13, wherein to enable the purge unit, the processor is configured to:

receiving a temperature of a wash unit refrigerant exiting an evaporator coil of the wash unit; and

draining a wash tank of the wash unit when the temperature of the wash unit refrigerant exiting the evaporator coil of the wash unit is less than a minimum temperature threshold.

20. The vapor compression system of claim 19, wherein to evacuate the purge tank of the purge unit, the processor is configured to:

providing a first control signal to close a first solenoid valve of the wash unit disposed between the condenser and the wash unit;

providing a second control signal to disconnect a second solenoid valve of the cleaning unit disposed between the cleaning tank of the cleaning unit and a vacuum pump of the cleaning unit; and

the vacuum pump is activated for a predetermined evacuation time.

21. A method of operating a purge unit fluidly coupled to a condenser of a vapor compression system, the method comprising:

(A) activating, via a processor of the vapor compression system, the purge unit having a purge duration of one hour; and then

(B) Continuing to return to step (a) in response to the processor determining that at least one wash unit drain occurred during step (a), or deactivating the wash unit via the processor for four hours in response to determining that a wash unit drain did not occur during step (a); and then

(C) Continuing to return to step (a) twice and then deactivating the wash unit via the processor for 24 hours in response to determining that no draining occurred during both times; and then

(D) Continuing to return to step (a) six times and then deactivating the wash unit via the processor for one week in response to determining that no draining occurred during these six times.

22. The method of claim 21, comprising:

(E) activating, via the processor, the wash unit having a wash duration of one hour; and then

(F) Continuing to return to step (a) in response to determining that at least one wash unit drain occurred during step (E), or deactivating the wash unit for another week in response to determining that a wash unit drain did not occur during step (E).

23. The method of claim 22, wherein activating the wash unit comprises:

activating a compressor and a condenser fan of the wash unit;

receiving a refrigerant temperature exiting an evaporator coil of the wash unit; and

in response to determining that the refrigerant temperature exiting the evaporator coil of the wash unit is less than a minimum temperature threshold:

closing a first solenoid valve of the purge unit disposed between the condenser and the purge unit;

disconnecting a second electromagnetic valve of the cleaning unit, which is arranged between a cleaning tank of the cleaning unit and a vacuum pump of the cleaning unit; and

the vacuum pump is activated for a predetermined evacuation time.

24. The method of claim 23, wherein activating the wash unit comprises: closing a solenoid valve associated with a drain line of the wash unit prior to activating the vacuum pump in response to determining that the refrigerant temperature exiting the evaporator coil of the wash unit is less than the minimum temperature threshold.

25. The vapor compression system of claim 1, wherein the third predetermined period of time is longer than the second predetermined period of time.

26. The vapor compression system of claim 13, wherein the second predetermined wait time is longer than the first predetermined wait time, and wherein the third predetermined wait time is longer than the first predetermined wait time and the second predetermined wait time.